<template>
  <div class="todo-footer" v-show="total">
    <label>
      <!-- <input type="checkbox" :checked="isAll" @change="checkAll"/> -->
      
      <input type="checkbox" v-model="isAll"/>
    </label>
    <span>
      <span>已完成{{doneTotal}}</span> / 全部{{total}}
    </span>
    <button class="btn btn-danger" @click="clearAll">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "MyFooter",
  props:['todos','checkAllTodo',"clearAlltodo"],
  computed:{
    total(){
      return this.todos.length
    },
    doneTotal(){
      return this.todos.reduce((pre,todo)=>pre + (todo.done?1:0)
      ,0)
    },
    isAll:{  //计算属性只用简写形式时有一个前提，计算属性只被读取，不被修改，所以用V-model进行双向数据绑定时会报错
      // return this.total == this.doneTotal && this.total > 0 
      get(){
        return this.total == this.doneTotal && this.total > 0 
      },
      set(value){
        this.checkAllTodo(value)
      }
    }
  },
  methods: {
  //   checkAll(e){
  //     this.checkAllTodo(e.target.checked)
  // }
    clearAll(){
      this.clearAlltodo()
    }
  },
}

</script>

<style scoped>
/*footer*/
  .todo-footer {
    height: 40px;
    line-height: 40px;
    padding-left: 6px;
    margin-top: 5px;
  }

  .todo-footer label {
    display: inline-block;
    margin-right: 20px;
    cursor: pointer;
  }

  .todo-footer label input {
    position: relative;
    top: -1px;
    vertical-align: middle;
    margin-right: 5px;
  }

  .todo-footer button {
    float: right;
    margin-top: 5px;
  }
</style>